1. Technical Field
The present invention relates to optical networks and more particularly to a wavelength division multiplexed passive optical network (WDM-PON) that delivers data and video services using subcarrier modulation at an optical line terminal (OLT) and parallel signal detection (PSD) at an optical network unit (ONU).
2. Description of the Related Art
With the expansion of user demands, access networks with much higher bandwidth than digital subscriber lines (DSL) and cable modems are needed. In particular, the need for providing emerging video services, including video on demand (VOD), high definition television (HDTV), and video blogs, further spurs the need for high bandwidth solutions.
With the growing amount of Passive Optical Network (PON) subscribers, annual sales of the PON equipment and sales are projected to grow accordingly. Transmission over such networks may be limited by the increasing data demand on existing passive optical networks. Limited bandwidth often results in limited services being provided to customers. Overcoming bandwidth issues by deploying additional fiber is often undesirable due to the large expenses associated therewith.
Furthermore, additional interfaces and/or equipment needed for additional optical fiber branches will further introduce ongoing management costs. Such costs are detrimental to providing broadband and other services in a competitive service provider market.
Conventional wavelength division multiplexed passive optical networks (WDM-PONs) use different receivers at different users. This contributes to the high cost of WDM-PONs solutions. To carry video signals to users, these WDM-PONs need a larger number of available wavelengths. For example, each user needs two wavelengths: one for data and one for video. To support n users, 2n wavelengths are needed. This increases the requirement for WDM devices in the system and therefore increases the cost of the WDM-PON.